@EIisabetta I'm inclined to believe it is done on purpose, in some kind of cheat-y way. I remember someone bringing this up in the "bug" thread and I'm pretty sure crinrict said that EA are "looking into it", and (to me anyway) it sounded like everyone's consensus is that the uploaders are certainly breaking SOMETHING to bypass the Modded tag.
I have a simblr and even the very "popular" CC users who upload their sims/houses to Gallery always make note of them being "Modded", so one would need to tick the "include CC" option to find the stuff. So if there was an easy honest way to un-Mod Modded content, I'm sure they would be doing that. I had a suspicion that maybe those who merge their CC avoid the "Modded" tag that way, but most of my friends on tumblr merge their CC and upload stuff that's "Modded".
Plus, if you go to the person's library, their offending uploads will not have the tag either. So it's not the "search" that removes the tags, it's the uploader.
"Modded" tag seems to be lax when it comes to sims, but it's is insanely hard to get rid of on lots. My CC-free lots used to get automatically flagged as "Modded" just because I had stuff in the Mods folder (completely unrelated to the build. They were cosmetic mods like smaller censor mosaic, removal of music notes and ZZZ's, and so on), so I would need to take out my Mods folder every time I wanted to upload a build. Also, did you know that if you take a photograph (using the Get To Work skill) of a CC object, that PHOTOGRAPH (essentially GTW object) will "become" CC? So if you take a photo of some CC sandals and try to use the photo in your retail store and upload it, your lot will be labeled as "Modded" unless you remove the photos. It's so bizarre. :/
